13
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livetrax/libs/pbd/ffs.cc

50 lines
1.3 KiB
C++

/*
* Copyright (C) 2013 Tim Mayberry <mojofunk@gmail.com>
* Copyright (C) 2013-2015 Paul Davis <paul@linuxaudiosystems.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "pbd/ffs.h"
#ifndef COMPILER_MSVC
#include <strings.h>
#endif
namespace PBD {
int
ffs (int x)
{
#if defined (COMPILER_MINGW)
return __builtin_ffs(x);
#elif defined (COMPILER_MSVC)
unsigned long index;
#ifdef WIN64
if (0 != _BitScanForward64(&index, (__int64)x))
#else
if (0 != _BitScanForward(&index, (unsigned long)x))
#endif
index++; // Make the result 1-based
else
index = 0; // All bits were zero
return (int)index;
#else
return ::ffs(x);
#endif
}
}